Animal Form and Function. Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organism Physiology is the study of biological.

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Presentation on theme: "Animal Form and Function. Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organism Physiology is the study of biological."— Presentation transcript:

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Animal Form and Function

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Diverse Forms, Common Challenges Anatomy is the study of the biological form of an organism Physiology is the study of biological functions an organism performs The comparative study of animals reveals that form and function are closely related.

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Animal form and function are correlated at all levels of organization Evolution of Animal Size and Shape – Different body plans have arisen during the course of evolution but these variations fall within certain bounds Physical laws constrain strength, diffusion, movement, and heat exchange – Ex. As animals increase in size, their skeletons must be proportionately larger to support their mass Evolutionary convergence reflects different species’ adaptations to a similar environmental challenge

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Example: Seal, Penguin, Tuna Water is 1000x denser than air and also more viscous. Any bump on animal may cause drag and slow them down. Natural selection often results in similar adaptations when diverse organisms face the same environmental challenges (convergent evolution)

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Exchange with the Environment An animal’s size and shape directly affect how it exchanges energy and materials with its surroundings (may limit body plan) Animal cells must have access to aqueous medium (substances dissolved diffuse and are transported across the cells’ plasma membranes) – Interstitial fluid

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Exchange with the Environment A single-celled protist living in water has a sufficient surface area of plasma membrane to service its entire volume of cytoplasm Two celled sacs and flat shape maximize exposure to surrounding medium (facilitate diffusion)

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Digestive system Circulatory system Excretory system Interstitial fluid Cells Nutrients Heart Animal body Respiratory system Blood CO 2 Food Mouth External environment O2O2 50 µm A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM). 10 µm Inside a kidney is a mass of microscopic tubules that exchange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). The lining of the small intestine, a digestive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM). Unabsorbed matter (feces) Metabolic waste products (urine) Anus 0.5 cm

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Hierarchical Organization of Body Plans Most animals are composed of specialized cells organized into tissues that have different functions Tissues make up organs, which together make up organ systems Some organs, such as the pancreas, belong to more than one organ system

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Table 40.1

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Exploring Structure and Function in Animal Tissues Different tissues have different structures that are suited to their functions Tissues are classified into four main categories: epithelial, connective, muscle, and nervous

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Coordination and Control Animal tissues, organs, organ systems must act in concert together. Coordinating activity across an animals body in this way requires communication (BIG IDEA!) between different body locations.

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Two major systems for coordinating and controlling responses to stimuli Endocrine (good for gradual changes such as growth, direction, etc.) – Releases hormones via the blood stream – Only certain cells are responsive to each hormone – Hormones tale second to act but can have long-lasting effects Nervous (good for rapid responses to environment) – Use cellular circuits involving electrical and chemical signals to send information to specific locations. – The information conveyed depends on a signal’s pathway, not the type of signal – Nerve signal transmission is very fast

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Figure 40.6 Response limited to cells that have the receptor for that signal. Conveys informatio n along a pathway.

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Feedback control maintains the internal environment in many animals Animals manage their internal environment by regulating or conforming to the external environment

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Regulating and Conforming A regulator uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation A conformer allows its internal condition to vary with certain external changes Animals may regulate some environmental variables while conforming to others

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Figure 40.7

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Homeostasis Organisms use homeostasis to maintain a “steady state” or internal balance regardless of external environment In humans, body temperature, blood pH, and glucose concentration are each maintained at a constant level

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Mechanisms of Homeostasis Mechanisms of homeostasis moderate changes in the internal environment For a given variable, fluctuations above or below a set point serve as a stimulus; these are detected by a sensor and trigger a response. (The response returns the variable to the set point.)

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Figure 40.8

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Feedback Control in Homeostasis The dynamic equilibrium of homeostasis is maintained by negative feedback, which helps to return a variable to a normal range Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off Positive feedback amplifies a stimulus and does not usually contribute to homeostasis in animals (does not reverse the change but drives a process towards completion, i.e. childbirth/uterus contractions)

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Alterations in Homeostasis Set points and normal ranges can change with age or show cyclic variation In animals and plants, a circadian rhythm governs physiological changes that occur roughly every 24 hours

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Figure 40.9

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Homeostasis can adjust to changes in external environment, a process called acclimatization Acclimatization is a temporary change during an animal’s lifetime, not be confused with adaptation. Ex. Elk moves us into mountains from sea level. Less oxygen. Breathing deepens. More CO2 lost through exhalation therefore raising pH above norm. Over days kidney function excretes more alkaline urine. Blood returns to normal pH.

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40.3: Homeostatic processes for thermoregulation involve form, function, and behavior Thermoregulation is the process by which animals maintain an internal temperature within a tolerable range

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In general, ectotherms tolerate greater variation in internal temperature, while endotherms are active at a greater range of external temperatures Endothermy is more energetically expensive than ectothermy

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Figure 40.10

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Variation in Body Temperature The body temperature of a poi kilo therm varies with its environment The body temperature of a homeotherm is relatively constant The relationship between heat source and body temperature is not fixed (that is, not all poikilotherms are ectotherms)

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Insulation Insulation is a major thermoregulatory adaptation in mammals and birds Skin, feathers, fur, and blubber reduce heat flow between an animal and its environment Insulation is especially important in marine mammals such as whales and walruses

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Regulation of blood flow near the body surface significantly affects thermoregulation Many endotherms and some ectotherms can alter the amount of blood flowing between the body core and the skin In vasodilation, blood flow in the skin increases, facilitating heat loss In vasoconstriction, blood flow in the skin decreases, lowering heat loss Circulatory Adaptations

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Cooling by Evaporative Heat Loss Many types of animals lose heat through evaporation of water from their skin Panting increases the cooling effect in birds and many mammals Sweating or bathing moistens the skin, helping to cool an animal down

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Both endotherms and ectotherms use behavioral responses to control body temperature Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat Behavioral Responses

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Both endotherms and ectotherms use behavioral responses to control body temperature Some terrestrial invertebrates have postures that minimize or maximize absorption of solar heat

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Adjusting Metabolic Heat Production Thermogenesis is the adjustment of metabolic heat production to maintain body temperature Increased by muscle activity (moving or shivering) Nonshivering thermogenesis takes place when hormones cause mitochondria to increase their metabolic activity (can produce heat instead of ATP)

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Figure Conclusion: Because oxygen consumption, which generates heat through cellular respiration, increased linearly with the rate of muscle contraction, the researchers concluded that the muscle contractions, a form of shivering, were the source of the Burmese python’s elevated body temperature. Results: The python’s oxygen consumption increased when the temperature of the chamber decreased. Her oxygen consumption also increased with the rate of muscle contraction.

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Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells Acclimatization in Thermoregulation

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Physiological Thermostats and Fever Thermoregulation is controlled by a region of the brain called the hypothalamus Group of nerve cells within hypothalamus functions as a thermostat. The hypothalamus triggers heat loss or heat generating mechanisms Fever is the result of a change to the set point for a biological thermostat

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Figure 40.16

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Concept 40.4: Energy requirements are related to animal size, activity, and environment Bioenergetics is the overall flow and transformation of energy in an animal It determines how much food an animal needs and it relates to an animals size, activity, and environment

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Energy Allocation and Use Animals harvest chemical energy from food Energy-containing molecules from food are usually used to make ATP, which powers cellular work After the needs of staying alive are met, remaining food molecules can be used in biosynthesis Biosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes

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Figure 40.17

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Metabolic rate is the amount of energy an animal uses in a unit of time Metabolic rate can be determined by – An animal’s heat loss – The amount of oxygen consumed or carbon dioxide produced Quantifying Energy Use

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Figure 40.18

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Minimum Metabolic Rate and Thermoregulation Basal metabolic rate (BMR) is the metabolic rate of an endotherm at rest at a “comfortable” temperature Standard metabolic rate (SMR) is the metabolic rate of an ectotherm at rest at a specific temperature Both rates assume a nongrowing, fasting, and nonstressed animal Ectotherms have much lower metabolic rates than endotherms of a comparable size

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Metabolic rates are affected by many factors besides whether an animal is an endotherm or ectotherm Two of these factors are size and activity Influences on Metabolic Rate

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Size and Metabolic Rate Metabolic rate is proportional to body mass to the power of three quarters (m 3/4 ) Smaller animals have higher metabolic rates per gram than larger animals The higher metabolic rate of smaller animals leads to a higher oxygen delivery rate, breathing rate, heart rate, and greater (relative) blood volume, compared with a larger animal

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Figure 40.19

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Figure 40.19a

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Figure 40.19b

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Activity greatly affects metabolic rate for endotherms and ectotherms In general, the maximum metabolic rate an animal can sustain is inversely related to the duration of the activity Activity and Metabolic Rate

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Different species use energy and materials in food in different ways, depending on their environment Use of energy is partitioned to BMR (or SMR), activity, thermoregulation, growth, and reproduction Energy Budgets

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Figure 40.20

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Figure 40.20a

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Figure 40.20b

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Torpor and Energy Conservation Torpor is a physiological state in which activity is low and metabolism decreases Torpor enables animals to save energy while avoiding difficult and dangerous conditions Hibernation is long-term torpor that is an adaptation to winter cold and food scarcity

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Figure 40.21

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Summer torpor, called estivation, enables animals to survive long periods of high temperatures and scarce water Daily torpor is exhibited by many small mammals and birds and seems adapted to feeding patterns